EPIC alleges that researchers at Cornell University and UC San Francisco, who worked with Facebook on the 2012 study, failed to follow standard ethical protocols for human subject research. Additionally, the organization contends that Facebook failed to disclose to users that their data would be shared with researchers or used for research purposes.

At the time of the experiment, Facebook was subject to a FTC consent order requiring the company to obtain express consent prior to sharing user information with third parties.

The complaint comes one day after Facebook COO Sheryl Sandberg brushed off the study as a small experiment and insisted that Facebook takes users’ privacy seriously.

Facebook experimented with the news feeds of 700,00 users in 2012 to see if negative status updates were catchy. According to data recently published in the Proceedings of the National Academy of Science, researchers found “experimental evidence of massive-scale emotional contagion through social networks.”

In other words, people can transfer their emotional state to others via social media without either party being aware.

The watchdog group is asking the FTC to impose sanctions, including a requirement that Facebook make public the algorithm by which it generates the News Feed for all users.

On Wednesday, Sandberg suggested that the research has been mischaracterized. “It has been communicated as an experience to shift emotions, it’s not exactly what it was,” she told NDTV. It was an experiment in showing people different things to see — to see how it worked. Again, what really matters here is that we take people’s privacy incredibly seriously and we will continue to do that.”